Impact of Photobiomodulation on Pain During Orthodontic Treatment.

Inclusion Criteria: * Systemically healthy male and female patients (age 20 to 65), i.e., do not suffer from systemic illness nor require medication during the saliva collection period. * Permanent dentition, with Little's Irregularity Index (LII) of 2 mm or greater for the upper and lower arch. * Orthodontic treatment using clear aligners via non-extraction therapy. * Patient is available for follow-up visits. * Patient is able and willing to comply with the requirements of this trial protocol. * Non-smoker with no use of chewing tobacco. * Good oral hygiene. * Caries free. * No sign of periodontal disease. Exclusion Criteria: * Systemic diseases * Medication use for the past 6 months; specially use of anti-inflammatory (e.g., NSAIDs), antiviral, antibiotics. * Smoking. * Active dental caries. * Any periodontal problem including bleeding, tooth mobility, bone loss, attachment loss, deep pockets. * Sleep apnea and other airway pathologies.